Blue Key
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How do you unlock Blue Key?
In The Binding of Isaac, Blue Key is unlocked by earning the The Beast completion mark as Tainted Cain.
Structured pathSource-backed requirements are mapped into trackable steps.
Doors can be unlocked without using Keys. Opening a door this way brings Isaac to an in-between room that resembles ???, with a few monsters.
What unlocking Blue Key leads to
Nothing depends on this yet.
Source: bindingofisaacrebirth.wiki.gg
Imported 2026-09-13